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User-Agent: Mozilla/4.77 [en] (X11; U; Linux 2.4.9 i686)
Description of problem:
On 09-10-01 I installed the security update which redhat released for
sendmail. I upgraded two RH6.2 systems from sendmail-8.9.3-20 to
sendmail-8.11.6-1.6.x.i386.rpm. After the upgrade. I tried to restart and
sendmail told me that it couldn't find the sendmail.cw file. I checked the
sendmail.cf.rpmnew file and saw that that information had moved to
/etc/mail/local-host-names. This was referenced in the new sendmail.cf
file. So I copied the sendmail.cf.rpmnew over sendmail.cf, luckily
preserving a copy. I restarted sendmail and everything seemed to be good.
These machines are web servers so most of the email is outgoing as opposed
to incoming.
Today, 09-12-01, I recieved a report that one of the mail aliases wasn't
working. I took a look as saw that my internal mail server was not able to
connect to the machine. I tried to telnet to the IP address and port 25.
The connection was refused. Which means the mail server was not accepting
external connections. I thought that was what sendmail.cw handled.
Finally I wound up reverting back to the version that had worked well
before because I was not really able to figure out how to make sendmail
accept the external connections that I needed.
Version-Release number of selected component (if applicable):
How reproducible:
Always
Steps to Reproduce:
1. install sendmail-8.11.6
2. copy over sendmail.cf.rpmnew to sendmail.cf, restart sendmail
3. try to connect to mail server using telnet hostname port 25
Additional info:

I have exactly the same problem.
Sendmail refuses to listen on anything but localhost.
It won't accept connections from outside.
Even adding the hostname+domain in /etc/mail/local-host-names
does not help: sendmail *only* listens on 127.0.0.* !
There is nothing special about my setup so I think there
must be many people experiencing the same problem.
greetings,
Rob van Nieuwkerk

I too have had this problem. Sendmail made no complaints upon starting up, but
refused all outside connections on port 25. I'm running RedHat 6.2, and still
running kernel 2.2.14-5.0. Everything else is upgraded to the latest
versions. My only solution to this has been downgrading to the previous
version.

I found the cause of the problem.
Starting with RH 7 sendmail does not listen to anything but
localhost by default. Apparently Red Hat just recompiled the
current sendmail SRPM also for the security fix that was made
for Red Hat 6.2. The sendmail that originally came with RH 6.2
does *not* have this default, so this can be very confusing to
6.2 users who applied this security update !! (RH are you listening?)
On http://www.redhat.com/support/resources/gotchas/7.1/gotchas-71.html
under the section "Sendmail Will Not Accept Outside Connections
After Installation" you can find the solution to the problem !
greetings,
Rob van Nieuwkerk

Nailed us too. (really would have been nice if the errate for the sendmail update warned about this.
For the short answer change this:
O DaemonPortOptions=Port=smtp,Addr=127.0.0.1, Name=MTA
to
O DaemonPortOptions=Port=smtp,Addr=0.0.0.0, Name=MTA
in /etc/sendmail.cf (the 8.9.3 install had it commented out, guessing that works as well)